Projectile



Nov. 27 1923. 1,475,578

R. A. HADFIELD ET AL PRO JJJJJ LE Filed Oct. 30, 1918 w f'z'G- 2.

Il M a! l g +5 Patented Nov. 27,1923.

' UNITED STATES PATENT OFFICE.

ROBERT ABBOTT HADI'IELD, OF WESTMINSTER, AND ALEXANDER GEORGE MCKENZIE JACK, OF SHEFFIELD, ENGLAND.

PBOJ'ECTILE.

Application fled October 80, 1918. Serial 1T0. 280,284.

To all whom it may comm:

Be it known that we Sir Roenn'r Aneorr HADFIELD, Baronet, F. S., and ALEXANDER Gnonon McKENzIn JACK, subjects of the King of Great Britian and Ireland, residing, respectively, at the city of Westminster, England, and Shefiield, in the county of York, England, have invented Im rovements in or Relating to Projectiles, of which the following is a specification.

When an armour piercing projectile perforates a hard faced armour plate, there is a liability of the base end of the projectile bein fractured and broken off in the region of t e front end portion of the groove in which the copper driving band is fixed, owing to the reduced diameter and consequent diminution in strength of the projectile in this region and to the extreme whi or blow that is thrown on to the base end 0 the projectile when passing through the armour plate, particularly in the case of angle fire.

Now the present invention has for its object to avoid or minimise liability to fracture of the base end portion of an armour piercing projectile in the region of the front end portlon of the driving band groove as above set forth.

For this purpose, an armour piercing projectile is provided with a driving band groove so constructed that whilst providing effective support for the rear end of the driving band and for preventing rotation of the band in the groove, as heretofore, the

front end portion of the groove, whilst ef- 4 fectually holding the front end of the driving band in place, shall be of relatively much less depth than heretofore so that the diameter and consequent strength of the projectile in the re ion of the front end portion of the groove s all be materially increased.

To this end, instead of making the driving band groove in the projectile of prac tically the same depth throughout in the direction of the length of the projectile as heretofore, it is made of decreasing dept in a forward direction, either gradually, as is preferred, or in steps or stages, so that the thickness or external diameter of the projectile at the bottom of the groove increases gradually or in steps or stages in a'forward direction from the rear end of the groove to the forward end of the groove where it is only slightly less in diameter than'the portion of the pro ectile adjacent to the front end of the groove, the depth of the groove at this part being sufficient to retain the front end of the driving band effectually in place.

In the accompanying illustrative drawings, Fig. 1 shows in longitudinal section and Fig. 2 in plan, part of an armour piercing projectile provided with a driving band groove and drivin band according to the invention. Fig. 3 1s a similar view to Fig. 1, showing a slight modification of the groove and band.

According to the construction shown in Figs. 1 and 2, the grooved portion a of the projectile b instead of being made of cylindrical shape, as heretofore and as indicated in dotted lines in Figs. 1 and 2, is, as shown in full lines, made of truncated conical shape with the larger end foremost, the bottom of the groove, as seen in a longitudinal section thereof (Fig. 1) being straight except where it is formed with the circumferential ribs or ridges c of waved or corrugated shape usually provided for preventing the driving band at rotating in the groove. The driving band (1, when applied to the projectile, as shown, fits closely against the ribbed conical bottom surface of the groove and against the ends a a of the groove, which are undercut as usual. In this case, the groove (1 instead of being of rectangular shape, as seen in a central longitudinal section of the projectile, will be of angular or wedge shape, as shown in full lines in Fig. 1. As will be seen from Fig. 1, the forward end of the groove is only slightly less in diameter than the external diameter of the adjacent portion of the body of the projectile and only suf- ,,ficient to enable the undercut forward end a of the groove to hold the thin forward end of the driving band d in place, thus affording the maximum possible thickness of wall of the body at this part which is in the neighbourhood of the forward end of the base plug with which the projectile is fitted. and therefore where the greatest possible strength of wall is essential in order to ensure satisfactory results when the projectile strikes an armour plate at a considerable angle. Under such condition of attack, the base end portion of the projectile is liable to be subjected to an exceedingly severe blow, a plied laterall thereto, by the edge of the ho e formed in t e armour plate by the 'onwardly moving forward portion of the projectile. Consequently, it is of the greatest importance that the wall of the shell at the part thereof where fracture thereof under the condition mentioned is liable to occur, .should be of the greatest attainable thickness and con uent strength,

consistent with other conditions to which the construction of the projectile must conform, as determined b naval practice. The external formation 0 the driving band d is not or need not be interfered with by reason of the difference in construction of the groove. If it be desired to maintain the normal radial thickness of the driving band at about the central portion of the length of the band, this can be readily provided for by making the groove of the desired depth at this part, the angle of the conical bottom portion of the groove being made such as to enable this result to be obtained. In this case the depth of the rear end portion of the groove will be relativel greater than usual but this will not be a isadvantage owing to the great mass of metal in the base end 6 of the projectile at this part of the groove.

In Fig. 3, the oove is shown as made of decreasing depti in a forward direction, in steps or stages a each step or stage being 0 cylindrical shape and of larger diameter than the one behind it. The construction of the groove shown in Figs. 1 and 2 is however preferred.

By reason of the construction described not only is the liability of the projectile to fracture in the region of the front end of the band groove avoided or minimised, but the projectile is made of greater constrictive strength at this'part, where every possible increment in constrictive strength is desirable if obtainable. Therefore, when detonation of the charge 'in the projectile takes place, the projectile, being considerably stronger at the part mentioned than before, will resist distention for a longer period than is possible with a projectile provided with a driving band groove as heretofore constructed, consequently the base plug of the projectile will not blow out so early and a better detonating effect generally will thereby be obtained.

What we claim is:

1. An armour piercing projectile of the kind having its body of substantially cylindrical shape and of uniform diameter to its extreme rear end, except where the drivin band groove is formed, wherein the base 0 the said groove is made of increasing diameter' from its rear end to its front end where the diameter. is only slightly less than the external diameter of the projectile bod 2. An armour piercing projectile o the kind having its body of substantially cylindrical shape and of uniform diameter to its extreme rear end, except where the driving band groove is formed, wherein the base of the said groove is made of conical shape, the diameter of the portion of the body at the bottom of the groove gradually increasing from the rear end of the groove to its forward end where it is only slightl less than the external diameter of the ad acent portion of the body.

3. An armour piercing projectile having a body of substantially cylindrical shape and of uniform diameter to the extreme rear end thereof except I where the driving band groove is formed, and consisting of one piece of metal, the base of said groove being made of conical shape and provided with integral circumferentially arranged ribs or ridges of waved or corrugated shape in the direction of their length, the diameter of the front 7 end of the conical base of the groove being only slightly less than the external diameter of the adjacent portion of the bod of the projectile, and a driving band fixe in said groove between the ends thereof and interlocked with said ribs or ridges.

Signed at London, England, this seventeenth day of September, 1918.

ROBERT ABBOTT HADFIELD. ALEXANDER GEORGE McKENZlE JACK. 

